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pm EM w Aug. 11, 1959 J. L. RUBRICIUS BLOOD LOSS DETERMINING DEVICEFiled Aug. 6, 1957 INVENTOR JEANETTE 1.. RUBRICIUS ATTORNEY 5 UnitedStates Patent 2,899,636 BLOOD LOSS DETERMINING DEVICE Jeanette L.Rubricius, Jamaica, N.Y.

Application August 6, 1957, Serial No. 676,559

5 Claims. (Cl. 324-30) The present invention relates to a method and anapparatus for determining the blood loss from patients during surgicaloperations after trauma and during childbirth.

In the field of surgery, it is important in many instances to ascertainthe amount of blood lost by a patient during an operation. Heretofore,such determination has been diflicult to make. During surgery, the majorportions of blood lost from patients is absorbed by sponges and gauzedisposed in the critical areas of the surgery and when these areremoved, a considerable amount of blood collected therein becomescoagulated making a volumetric determination of the blood a dimcultproblem.

Accordingly, it is an object of this invention to produce an apparatusand a method of accurately determining the blood lost from a patientduring a surgical operation.

Another object of the invention is to provide a method and apparatuswhich will accurately and continuously determine the amount of bloodlost from a patient at any unit of time during surgery.

Still another object of the invention is to produce an apparatus fordetermining blood loss during surgery which is simple to operate and maybe fabricated easily and economically.

In a preferred embodiment, the invention comprises a container. with anagitator adapted to extract blood from sponges, gauze and the like,means connecting the container to a suction device which is incommunication with an operating site, electrodes positioned within thecontainer and connected with a mil-balancing conductivity bridge througha servomotor whereby the conductivity of the solution may be read interms of blood loss.

Certain other advantages and objects will become apparent from thefollowing detailed description of the invention and the accompanyingdrawing showing a partially cut-away and schematic illustration of theinstant invention.

Referring to the figure, there is shown an exterior housing '10 havingan opening in the top portion thereof adapted to receive acontainer 12.The container 12 is provided with an outlet passage 14 formed in thebottom wall thereof with a screen protector 15 mounted on the inner sideof the container. A vacuum pump 18 is provided having communication withthe outlet 14 through a coupling pipe 16. The pressure side of the pump18 is provided with a pipe 20 which extends upwardly and passes throughthe exterior of the housing 10. It will be noted that the pipe 20 isprovided with a curved end portion 24 which is pivotally mounted to thepipe 20 by means of a swivel coupling 22.

The inlet side of the pump is connected to a suction pipe 26 which isprovided with a valve 28. The pipe 26 is adapted to extend to theoperating site and is employed to provide a path for blood lost directlyat the operating site to the container 12 through the suction pump 18,pipe 20 and the curved outlet 24.v

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A motor 30 is mounted on the exterior side wall of the container 12 andis adapted to drive an agitator member 32 which is disposed on the innersurface of the container and may be driven by a conventional outputshaft of the motor 30. The agitator member 32 may be of the conventionaldesigns, such as, for example, the agitator members of the smallapartment size Washing machines.

In practice, the container 12. is initially filled with a measuredvolume of distilled water 34 or any substance of known electricalconductance or resistance.

It has been found advantageous to place a perforated basket 36 in thecontainer 12 so that the gauze sponges disposed therein are containedand are not allowed to float loosely in the container in which case theyhave a tendency to plug the drain 15. The basket 36 may be formed ofscreen or other perforated material. The basket 36 enables the spongesto be readily removed from the container 12 after they have beencompressed of their fluid at the conclusion of an operation and may thenbe easily and quickly counted. In addition, the basket 36 provides meanswhich militate against the splashing of the fluid 34 when the levelthereof is beneath the agitator 32 as in emptying.

The basket 36 is provided with a flanged rim 38 adapted to rest on theupper marginal edge of the container 12, thereby permitting the mainbody of the basket 36 to be suspended within the container.

An A.C. Wheatstone bridge circuit is employed to measure theconcentration of blood which is present within fluid 34 in the container12. The Wheatstone bridge is a balanced circuit including three knownresistances and one unknown resistance with a source of current at linefrequency and a device for detecting the potential difference. In thisWheatstone bridge circuit, a conductivity cell 40 constitutes one arm.Another arm consists of a temperature compensator 42, which may beeither automatic or manual. The third and fourth arms, 44 and 46,respectively, consist of calibrating resistors and a variable resistance48. The variable resistance 48 is a calibrated slide wire arrangement.The Wheatstone bridge circuit is energized with a power supply(alternating current) which is connected be-. tween the conductivitycell 40 and the fourth arm resistor 46 and the temperature compensator42 and the third arm resistor 44 in the conventional manner. The outputof the Wheatstone bridge network is sensed across the bridge at thepoint on the variable resistance 48 determined by the slide wire contact50 and the point 51 between the conductivity cell 40 and the temperaturecompensator 42. Any voltage resulting from an unbalance in the bridgenetwork is applied to the primary winding of a transformer 52 whichfeeds a signal proportional to the unbalance to an amplifier 54. Theoutput of the amplifier 54 is operative to energize a motor 56 which isof a reversible type. A negative going signal fed to the motor 56 isoperative to energize the motor in one direction while a positive goingsignal is operative to drive the motor 56 in the opposite direction.

The motor 56 is mechanically coupled to the sliding contact 50 of thevariable resistance 48 and also to a meter 58 which is calibrated interms of blood loss. The armature of the motor 56 is directly coupled tothe meter 58 so that the rotation of the armature Will causesimultaneous movement of the indicating needle of the meter.

It has been found that by using distilled water in the container 12 theinitial conductance of the fluid 34 is negligible. Any subsequentchanges in conductivity are brought about by the addition of blood intothe fluid. When the blood, which is two phase, consisting of both cellsand serum, is added to the distilled water the blood becomes hemolysed;IIhat isythe red blood cells'are ruptured by diluting the whole bloodwith water, thereby liberating the intracellular electrolytes into thesolution and thus varying the conductivity of the fluid 34 within thecontainer 12. Since the initial conductance of the water known, thequantity of water is known, the conduc'tance of the blood added isknown, the only unknown uantity is the amount of blood which has beenadded;

It will be appreciated that during an operation, blood soaked sponges,gauze and the like may be manually disposed within the container 12 andwill be agitated by the agitator '32 so that the blood clots and fluidblood may be removed therefrom and become a portion of the fluid 34. 'Itwill also be appreciated that by connecting the pipe 26 to the operatingsite, the vacuum pump 18 will be operative to suck the blood from theoperating site through valve 28 through the pipes '26 and '20 outthrough the outlet end 24 into the fluid 34 within the container 12. Asthe blood content of the fluid 34 varies, the conductivity of the fluidwill likewise vary proportionally. This change in conductivity may besensed by the conductivity cell 40 which forms one arm of the Wheatstonebridge network.

In operation, the bridge is initially balanced so that the output E willbe nearly zero. When the blood content of the fluid 34 is increased theresistance changes in the measuring arm and likewise the voltage Eincreases. The phase of this voltage is determined by the direction ofchange of the resistance. The resultant voltage output of the bridge isamplified by the amplifier 54 and is fed to the field winding of thereversible motor 56. The motor 56 is mechanically connected to the armof the slide wire resistor 50 and is driven in a direction that willreduce the voltage, E to again be nearly zero. Simultaneously withbalancing the bridge, the motor 56 drives the meter 58 which has beencalibrated in terms of blood loss. When the voltage E becomes zero, themotor 56 will stop, thereby allowing a positive and continuous readingof the meter 58 during the course of an operation of the blood loss. Itwill be readily apparent that the motor 56 may, in certain instances,overcorrect in which case the bridge unbalances in an opposite directioncausing the motor 56 to reverse to completely balance the bridge throughthe variable resistance 48. In such case the indicating needle of themeter 58 will return to its proper position in unison with the motor 56properly indicating the amount of blood contained within the container12.

The temperature compensator 42 is in the circuit to electrically correctfor changes in the temperature of the solution. The compensator 42adjusts for temperature through the change of resistance of thecompensator, which may be a thermistor, .inserted in the fluid 34.Either the manually adjustable type of resistance or the thermistor maybe used in the instant circuit without departing from the scope of theinvention.

Upon the termination of an operation, it is necessary to remove thefluid 34. To this end, the curved pipe 24 is turned to the positionshown in dotted lines, the pump 18 is energized, and the fluid 34 maythereby be conveniently removed from the container 12.

While the illustrated embodiment of the invention shows the conductivitycell 40 and the temperature com pensator 42 positioned within thecontainer 12, it will be apparent that the objects of the inventionmaybe likewise achieved by disposing these elements within the pipe 16.

It will be clearly apparent from the above description that theinvention herein set forth produces a new, novel and eflicient methodand apparatus for determining accurately during the course of anoperation or childbirth the amount of blood which is lost by thepatient.

I claim:

1. An apparatus for determining blood loss comprising in combination, acontainer, at fluid contained within said container, a fluid imperviousbasket disposed within said container, agitator means disposed withinsaid container for extracting blood from blood soaked materials disposedwithin said fluid, suction means for providing communication betweensaid container and an operating site, a null-balancing conductivitybridge circuit, and electrodes disposed within said container andforming at least one arm of said bridge circuit for detecting changes inconductivity of said fluid. I

, 2. An apparatus for determining blood loss comprising a container forcontaining a fluid, a fluid impervious basket disposed within saidcontainer, an agitator disposed within said container, means providingcommunication with said container and an operating site, a nullbalancingconductivity bridge circuit, one of the arms of said circuit including aconductivity cell disposed within said container, another of the arms ofsaid circui-t including a'temperature responsive resistance elementdisposed within said container, and means c'onnec'tedto said bridge formetering any unbalance thereof.

3. An apparatus for determining blood loss comprising a container forcontaining a fluid, an agitator disposed within said container, meansproviding communication with said container and an operating site, meansfor recirculating the fluid contained in said container, anull-balancing conductivity bridge circuit, at least one arm of-saidbridge including a conductivity cell, said conductivity cell disposedwithin said container, and means connected to said bridge for meteringany unbalance thereof.

4. .A method for determining blood loss during surgical operationsconsisting of adding blood to a fluid of known electrical conductivity,agitating the blood to liberate the intercellular electrolytes andprotein and continuously sensing the conductivity of the composite fluidby a null-balancing conductivity bridge circuit whereby the amount ofbloodin said fluid is determined.

5. A method of determining blood loss during a surgical operationcomprising introducing lost blood and blood-soaked materials into a bodyof fluid in a confined zone whereby the blood is diluted andintercellular electrolytes and protein are liberated into the fluid,continuously sensing variations in the electrical conductivity of thecomposite fluid in said confined zone, and utilizing the variations inelectrical conductivity to determine the amount of blood collected insaid zone.

References Cited in the file of this patent UNITED STATES PATENTS2,192,123 Bennett Feb.'2 7, 1940 2,621,235 Jewell Dec. 9, 1952 2,687,139Noble et a1 Aug. 24, 1954 UNITED STATES PATENT OFFICE CERTIFICATE 0F CUECTIUN Patent No, 2,899,636 August 11, 1959 Jeanette Lo Rubricius It ishereby certified that error appears in the printed specification of theabove numbered patent requiring correction and that the said LettersPatent should read as corrected below.

Column 4, lines 12 and 22, for "impervious", each occurrence, readpervious Signed and sealed this 12th day of January 1960a (SEAL) Attest:

KARL H, AXLINE ROBERT C. WATSON Commissioner of Patents AttestingOfficer

